mcdougall



- 2 Sheets-fSheet 2.. l. T. McDOUGALL.

Furnace.

Patented Dec. .4,- 1866.l

@nimh 13125 -gatrnt @frn y IMPROVED FURNAGE.

JAMES T. ll/ICDOUGALL, OF SAN FRANCISCO, CALIFORNIA.

Letters .Patent No. 60,219, dated December V4, 1866. i

SPECIFICATION- TO ALL WHOM IT MAY CONCERNz.

Be it known that I, JAMES T. McDoUGALL, of the city and county of San Francisco, State of California, have invented certain new and usefullmprovements in Reverberatory Furnaces" for the reductionV of ores and refining of metals; and I do hereby declare that the following description and accompanying drawings are sufficient to enable any person skilled in the art or science to which it most nearly apnertainsto make and use my said invention without further invention or experiment.

The nature of my said invention consists of the following-described improvements, that is to s ay, my furnace is constructed so that it rests on rockers, and by the use of levers can be made to move from side to side by a tipping or cradle movement, as desired. By this arrangement the metallurgist is enabled to` change the melted metals or minerals from onel point or side of the hearth to the other, thereby agitating the contents, l

and bringing thc material to be operated upon into immediate contact with the reducing and rening agents. It also greatly facilitates the removal of the slag and metal from the furnace, and in a great degree dispenses with the use of rabbling irons, which are very expensive, because of the rapid decomposition that they undergo when immersed in a liquid sulphurettedfmetal, and the counteracting effects of the material that they add to the` metallic bath. My invention also relates to anew arrangement for the smelting and refining hearths, combining the two in one, with an elevation or dam-wall between;A also, to a new device for feeding the fuel, ores, and .fiuxes to the furnace, the fuel having first been deprived of its moisture, and the external air excluded during the process ofA feeding. Lastly, my invention relates to a new arrangement for `securing the furnace from the injurious effects produced by expansion and contraction.

Referring to the drawings- Figure 1 is a top view of my furnace, with the portion above the line of the hearth removed, taken in the line 3, 4, iig. 6.

Figure 2, a side section, taken in fthe line 1, 2, fig. 5.

`Figure 3, a cross-section, taken in the line 5, 6, iig. 5.

Figure 4, an end view.

Figure 5, a top view or plan.

Figure 6, anelevation. v

Figure 7, a chimney piece or shield.

Figure 8, feeding rod for ores and iiuxes.

Figure 9 shows device for feeding'fucl to furnace.

I construct my furnace of fire-bric iron, enclosing both ends and all of that portion below the line of the doors,` conforming in shape tothe interior arrangement, having a continuous hearth A C, `with division A is the smeltiug hearth, beginning `at the bridge-wall G, having a gradual inclination in the direction of the chimney E suliicient to allow the liquid portion of the mineral undertreatment to flow freely in that direction, near its junction with that portion C called the refining hearth, where it again rises, forming a ridgeor dam-wall B, extending from sidevto side across the hearth, and having a height about the same as the end nextpto the bridge-wall. The refining portion of the hearth C is in shape half oval, conforming in width to that portion called the dam-wall, and terminating abruptly against it where the two join, but having a somewhat lower level than any other portion of the refining hearth, and extending back from thedarn-wall to the chimney flue D. The object of this arrangement is to give less depth to the metallic bath as the heat decreases in intensity; also to facilitate the drainage of metals toward the door hearth H H, where they are drawn off by a movement from side to side of the furnace. `The doors T T are for the purpose of drawing oi .the slag and metals, as well as to watch the operation of` smelting` and refining, and may be stopped by anyrwell-known method.

For supplying the fuel to my furnace I employ a cylinder N, figs. 2, 9, made of iron or other suitable material, having an opening longitudinally for about one-third of its circumference, with head-pieces. This cylinder is placedtat a suitable distance above the fire-grate F, and is made to revolve in asegment of a circle, hollowed out at the front end of the brick `lining of the furnace, so arranged that when it is turned over thecontents will be emptied into the grate. Ordinarily the cylinder will be placed so that one-halfof its diameter will be within the outer casing of the furnace, and over it a cover or case X, (shown in figs. 2,4, 5,) conforming in shape, and

k, or other suitable refractory material, with an outer shell or cover of i Lhung upon hinges, so that it will-fall over the cylinder, shutting closely. .The contents of the cylinder are emptied Ainto the grate through the chute P by means of the handle Y. In this manner the external air is prevented from reaching the cylinder in suicient quantities to cause combustion, and as the contents are replenished immediately after being or having been discharged, the succeeding charge will be submitted to a considerable degree of heat during the interval between firing. A small pipe, c, (iig. 5,) leads from one end of the cylinder over the top of the furnace, which conducts the Ysteam Aand vapor into the vchimney near the neck of the furnace. By this arrangement the fuel will be deprived of its watery combination, rendering it suitable for ready combustiomand less liable to crack or splinter, in which case it fallsl unconsumed below the fire-grate and is wasted.

I conceive that the principle to be governed by for'supplying the ore and fluxes to the Asmelting hearth must be just in proportion to the amount of caloric generated. ACareful and repeated trials have fully demonstrated that during the perfect combustion of one pound of goed bituminous coal sufficient caloric is evolved to raise the temperature of four pounds of material, requiring 2880,? Fahrenheit for its fusion, from 32 Fahrenheit tc its melting point, or, 1n other words, to melt cast iron. For example, supposing that a working furnace can be maintained at a steady temperature of 2900o Fahrenheit by a consumption of one hundred and fifty pounds of fuel per hour, and that the consumption be increased onehundred and fifty pounds per hour, making three hundred pounds, then the full reducing capacity ,'will'be just six hundred'p'ounds of ore perhour. Now, if the furnace be fed just in proportion to the increase of the heat, then it follows, by an immutable law of equivalents, that the capacity for immediate reduction is equal to the increase of temperature, deducting, however,

only the heat abstracted by the conduction and radiation of the feeding process. With these facts in view, and

to accomplish the'desiredobject, I employ a wedge-shaped hopper V, with feeding rod or bar W, fig. 8, usually to be attached to the side of my furnace, in such a position 'that the round bar running across the very bottom will enter the furnace about midway between the bridge-wall and dam-wall, about on a level with the top of the bridge-wall, of suiiicient length to reach nearly across the smelting hearth. In this bar there is a groove or hollow, with a handle at one end, worked by hand or machinery. When the hopper, which contains the matc- 'rial is prepared for smelting, the man attending gives the bar a forward movement into the furnace, with the groove upward, filled with material; then, by a quick turn either to the right or left, the contents are deposited onto the smelting hearth' asdesired, the barA being quickly withdrawn, groove downward, and the same operation repeated as often as required. In a furnace reducing six hundred pounds per hour, and the bar carrying ten pounds per stroke, .there will of course be required one stroke per minutef Now, as the stroke can easily be made. in dfteen seconds, it'followsthat the bar can never attain a temperature of more than one-fourth of that of the furnace. From this temperature vmust be deducted the calorie lost by conduction and radiation. It is found by experimental tests that when the temperature of the furnace is suicient to fuse cast iron, that one stroke per minute failed to keep lad in a constant state of fusion in the hollow of the bar. Repeated and long trials have fully demonstrated that this principle applied will of itself -save fty per cent. of fuel in smelting ores in a reverbcratory furnace. I also apply the above-described invention or apparatus for supplying iiuxcs to the refining hearth, (when required,) which is placed upon the oppositeside of the furnace, marked W, fig. 5, entering vthe hearth'. In theA `reduction of some ores my -feed hopper may be placed immediately over the smelting hearth, and the revolving motion only given to the bar. In such an event the ore will be dropped through a chute onto the hearth.

I construct a movable shield L, figs.` 6, 7, in order to accommodate the movement ofthe furnace to a lstationary chimney, whichk restson an independent segment of a circle ofthe same diameter as the rockers of the furnace, the head of the shield fitting the neck, and sufficiently large to cover the aperture in the chimney when the furnace is in movement.- .Y

An outer shell or case of iron is placed around the furnace, below the line of the working doo-rs, conform- 'ing in shape to the interior, covering both ends excepting the necessary apertures for working. The object `of this is to make the furnace very compact, dispensing with a vast amount of dead-wall and cumbersome material used in other methods of building reverberatory furnaces. It also vkeeps the bridge-wall and hearth, as well as 'the lower portions of the furnace, firmly in place; likewiseprevcnts leakage, and affords a secure fastening to the frame upon which. it rests; also a place to attach the longitudinal and cross-bars, preventing the injurious.

effects of expansion and contraction.

To secure my furnace I employ bands of iron a a a, 85e., b b b, placed longitudinally and at right angles.. b b b are placed longitudinally, commencing near the line ofthe bridge-wall and passing down to the flue a a a, dto., are placed atright angles, the whole conformingwith the actual shape of the furnace, passing over the topnndcr the longitudinal liron strap g,securcfl with keys driven under the lower edge of the iron shell orcase,

affording thefacilities for firmly securing the fire material above the iron casing, and any other appliances of the furnace, as well as binding the whole closely together.

The furnace is placed upourockers R R R, dto., having braces O O, 85e., (iig. 2,) constructed of iron or other suitable material, having concave bearing surfaces, and resting on convex rails or bars S S, &c. By this arrangement it meets the longitudinal expansion, and either in expansion or contraction readjusting itself, and the bearing surfaces are always of the same dimension.

The movement of the furnace from right to left, or side to side, is' effected by levers introduced into the sockets d d, underneath and at the front end, the former to4 be worked by a bent and the latter by ,a straight lever. The door hearths and supports are secured to the side of the furnace at snflicient distances below the working floors to sustain and keep in place the clay door hearths H H. v

If found necessary a blast, instead of the draught of the chimney, may be used, by means of a hose or iiexible joint, attached at N, iig. 1, to accommodate itself to the movement of the furnace.

Having thus `described my improved Reverberatory Furnace, what I claim, and desire to secureby Letters Patent, is v l 1. I claim a, smeltng hearth of 'peculiar' construction, A B, the sloping portion A inclining toward C; its lower portion forming the dain-wull or ridge B, running across the hearth of the furnace from side tosde, substantiallyus describedl and for the purposes set forth.

2. I claiin the half-ovel-shaped refining hearth O, conforming in shape to the smelting hearth where theyV i smelting hearth A, for the purposes specified and set forth.

3. I claim the manner of feeding the uxes and ores to the furnace by the' use of `the hoppers V V und grooved bars or rods W W,` substantially as described. i

4. I claim the devices for feeding the fuel to the furnace, `und depriving it of its moisture, by the use Vof the cylinder N and conducting pipe c, (or their equivalents,) as herein specified and shown. i

5. The arrangement of the door hearths H H, for discharging the metal and slag, siibstaintiullyas described.

6. The. manner of Abinding the said furnace with bands of iron secured to the casingbf. the furnace `and keyed beiowit, when arranged substantially as described and for the purpose setforth.

7'. Theconcave rockers R R R, and convex rails S S S, with chimney shield L, und lever sockets d d.

join, the sole of which has a. slight inclination from the flue D toward B, where it` has a, lower level than `the Lastly, I claim the within-described improvements, whether employed singly or in combination, in smelting I furneces,-substo.ntially sind for the purposes herein specified. i

In witness whereof I have hereunto set my hand and seal this 27th day of February,"A. D. 1866.

' l JAMES] T. MCDOUGALLI [1.. 5.] Witnesses:

C. W.- M. SMITH, Gos. A.' MANTHEY. 

